Advanced coking technology for coal slime

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I. The purpose and significance of converting low-quality coal slime into high-quality clean energy. The extraction and use of coal have played a significant role in the development of human civilization. However, to date, the utilization techniques for coal slime, which is a by-product of all coal washing plants, remain at the same primitive level as that of using coal directly. Due to the low calorific value of coal slime (usually 3000–3500 kcal) and its high moisture content, long-distance transportation is not cost-effective. Therefore, over the years, large amounts of coal slime have been directly burned for cooking, heating, and in various heat-consuming industries by the people living in coal mines and the surrounding areas. Not only is the thermal energy utilization rate low, but it also causes severe environmental pollution. Therefore, how to transform low-quality coal sludge, which has a poor calorific value upon direct combustion and causes severe environmental pollution, into high-quality clean energy is an urgent problem that needs to be solved. Environmental protection is a fundamental national policy in our country; improving the efficiency of resource utilization is therefore of great practical significance and profound historical importance, making the application of this technology highly relevant. Tests on compacted coking coals revealed that the slime had good cohesion; an iron box test was conducted, and then combustion comparison experiments were carried out between the resulting honeycomb coke and ordinary smokeless honeycomb coal, yielding satisfactory results. Since coal slime is mainly composed of medium-sized coal particles, it has a low grade, low volatil content, and high moisture content, making it unsuitable for being processed using conventional equipment into a clean energy source that meets environmental standards. Through experimental research, successful breakthroughs were achieved in two aspects. First, the research successfully identified a technological approach suitable for the further processing of coal slurry ； Second, advanced technical equipment designed to enable further processing of coal slime in conjunction with this technology was researched, developed, manufactured, and installed—the TS rammed coal horizontal coking furnace. The proper resolution of these two issues **increases the value and utilization rate of coal slime, and enables the recovery of various chemical raw materials, thereby completely eliminating the problem of burning coal slime and producing black smoke that existed in traditional coal usage. It creates favorable conditions for the civilized use of coal, efficient energy utilization, resource conservation, and environmental protection. II. Technical and economic indicators for the deep processing of coal slime This technology is highly advanced. Due to the high moisture content in coal slime, a large amount of heat is required for coking. Moreover, coal slime contains a high proportion of medium-grade coal particles, which results in a low grade and low calorific value, as well as low volatile matter content. Therefore, when using conventional coking techniques and equipment to process coal slime, the gas produced cannot meet the heat requirements needed for the coking of coal slime with high moisture content. To this end, the following technical approach was adopted: 1. Depending on various requirements and the different uses of the products, the coal slurry is first compacted into briquettes of different shapes (such as those in the format of honeycomb briquettes available on the market). By doing this, it is possible to reduce the moisture content of the coal slime ； Secondly, it can reduce the gaps between coal particles, increase their density and improve their strength; as a result, more coal slurry can be coked in the same volume of coking chamber ； Third, it can improve the quality after coking. 2. Depending on the type of coal, an appropriate degree of carbonization can be selected for adjustment. On the one hand, it ensures that coal sludge is processed into high-quality clean energy; on the other hand, it guarantees that the gas produced can meet the heat requirements of the coking process. 3. The coking equipment of the TS rammed coal horizontal coking furnace has low heat consumption, and the gas produced is sufficient to meet the heat requirements for coking coal slurry with high moisture content. The heat required to coker one kilogram of coal slurry at 1000°C has been reduced to around 500 kcal. Additionally, 1.5%–2% of coal tar, as well as some light oil and coal tar pitch, can be recovered, with no wastewater generated and no black smoke emitted.